This study examines variation in Spanish future-in-the-past expression across six centuries in order to determine if this variation parallels canonical future variation diachronically. Future-in-the-past tokens in the conditional (e.g., iría “would go”) and imperfect go-periphrasis (e.g., iba a ir “was going to go”) were extracted from two corpora and coded according to factors known to condition the variation between synthetic future (e.g., irá “will go”) and periphrastic future (e.g., va a ir “is going to go”). Results indicate a rise in the use of the periphrastic form, analogous to the rise in the use of the periphrastic future. Additionally, most factors previously reported to influence canonical future variation were found to play a comparable role in future-in-the-past variation over time.